Ribbon feeding mechanism



Nov. 5, 1968 R. H. MCLEAN 3,409Q113 RIBBON FEEDING MECHANISM Filed March16, 1966 2 Sheets-Sheet l Y CLUTCH INVENTOR RONALD H. LEA

33D BY C ATTORNEYS R. H. MCLEAN Nov. 5, 1968 RIBBON FEEDING MECHANISM 2Sheets-Sheet 2 Filed March 16, 1966 INVENTOF? RONALD H. MCLEAN BY mmATTORNEYS United States Patent O 3,409,113 RIBBON FEEDING MECHANISMRonald H. McLean, Newington, Conn., assiguor to Litton Business Systems,Inc., a corporation of New York Filed Mar. 16, 1966, Ser. No. 534,808 2Claims. (Cl. 197-151) ABSTRACT F THE DISCLOSURE In a typewriter ribbonfeed mechanism, a slip drive having a plurality of cantilever mountedarcuately shaped ngers extending radially in the same circular planefrom hands symmetrically disposed around the circumference of a iirsthub which is positively driven, to frictionally engage a second hub, thefingers rotating the second hub with the first hub and slipping -inresponse to load on the second hub.

This invention relates to a ribbon feeding mechanism for a carbon ribbonand more particularly to a mechanism for tightly winding the ribbon ontoa take-up spool, and more specically to a mechanism for permitting theribbon take-up spool to slip with respect to a take-up spool drivingmember when the ribbon is not being fed.

Carbon ribbon is being increasingly used on correspondence typewritersbecause of the excellence and clarity of the copy produced thereby.Unfortunately, this type of ribbon may only be used once, and thereforeit is desirable that the take-up spool accommodate at least all of theribbon being ldispensed from the supply spool so as to minimize thenumber of disposals of used ribbon from the take-up spool. To accomplishthis objective with a take-up spool of similar dimension as the supplyspool, the run of the carbon ribbon between the ribbon index rollers andthe take-up spool must be maintained under tension thereby to wind theribbon as tightly as possible on the take-up spool. Moreover, since thetake-up spool may be driven through a larger angle than that of theribbon feed rollers, pursuant to the changing diameter of the take-upspool as the used ribbon is wound thereon, a means for slipping thetake-up spool with respect to its drive must be provided to maintain thetension and still prevent tearing of the ribbon.

In accordance with the invention there is provided a slip drivecharacterized by a plurality of cantilever mounted arcuately shapedfingers which lie in one and the same circular plane. The fingers may beintegrally supported within a housing hub of a driving member andadapted to couple to an engaging hub on a take-up spool or alternativelythe ngers may be integrally supported within a housing hub of thetake-up spool, and in this event an engaging hub would be formed on thedriving member. In either case, the hub and lingers form a releasablysecuring drive which permits the take-up spool to rotate when the ribbonindex rollers feed the ribbon and to slip with respect to the rotatingdrive member whenever the index rollers are not feeding ribbon.

Accordingly an object of the invention is in the provision of a s'lipdrive which permits uniform feeding and tight winding of ribbon on atake-up spool.

Anot'her object of the invention is to provide a drive for rotating aribbon take-up spool only when the ribbon is being advanced.

Still another object of the invention is in the provision of a slipdrive which permits slip between a take-up spool and the take-up spooldriving member.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following ice detailed description when considered inconnection with the accompanying drawing in which like referencenumerals designate like parts through out the gures thereof and wherein:

FIGURE l is a fragmentary front elevation showing a carbon ribbon supplyand take-up spool operatively mounted to portions of the frame of atypewriter;

yFIGURE 2 is an outside left elevation of the carbon ribbon take-upspool, the ribbon index Wheels, and the gear train for driving the indexwheels;

FIGURE 3 is a fragmentary elevational View showing the slip drive;

FIGURE 4 is a fragmentary elevational View similar to FIGURE 3 showingthe slip drive engaged with the take-up spool hub; and

FIGURE 5 is a fragmentary sectional View taken along line 5 5 of FIGURE4 showing the slip drive and takeup spool assembly on a frame mountedspindle.

Referring now to the `drawing wherein like reference numerals designatelike or corresponding elements throughout the several views and whereina preferred embodiment is illustrated, there is shown in FIGURE 1 atypewriter frame 10 which rotatably supports on the right side of themachine a carbon ribbon supply spool 11 associated `with conventionaldrag means (not shown), which prevents too rapid turning of the spool. Aribbon 12 from the supply spool is directed around a right guide roller13, through a ribbon vibrator structure generally designated byreference numeral 14 and around a left guide roller 1S. As viewed inFIGURE 2, the ribbon after passing around the left guide roller, shownin FIGURE l, passes between ribbon indexing rollers 16 and 17, whichnormally grip the ribbon and permit a predetermined amount of ribbon tobe drawn from the supply spool 11 during each type stroke. Moreparticularly, the roller 16 is supported for rotation on a bracket (notshown), which is spring biased toward roller 17, and roller 17 isrotatably mounted on a shaft 18 and indexable on each type stroke,whereby the ribbon is permitted to be drawn between the rollers andwound on a take-up spool 27 whenever roller 17 is indexed. The roller 17is integrally formed with an indexing roller drive gear 41, which formsa part of a gear train, generally designated by reference numeral 19,and comprised of a pinion 33 driving a pair of identical intermediategears 39 and 40, which in turn drive the roller drive gear 41 (FIGURE2). Pinion 33 is integrally formed with a take-up spool gear 28, whichis driven by a drive gear 20 mounted to rotate with a shaft 21 (FIGUREl) when a clutch 22 is actuated on each type stroke, by a conventionalmechanism well known in the art, thereby coupling shaft 21 to aconstantly rotating power shaft 23. Thus, the indexing roller 17provides a uniform ribbon feed on each type stroke, and inasmuch as thetake-up spool diameter is constantly increasing as the used ribbon iswound thereon, and it is desirable to maintain a length of ribbon 24taut between the index rollers and the take-up spool, the ratio of geartrain 19`is designed to drive the index roller 17 through a much smallerangle than the angle through which the take-up spool gear is driven.Consequently, a slip drive, generally designated by reference numeral34, must be provided to permit the take-up spool to slip, with respectto the rotating take-up spool drive gear, thereby maintaining the ribbontaut at all times, as will be described below.

Referring now to FIGURES 3 through 5 which best show the structuraldetails of the invention, the take-up spool gear 28 is preferably madeof plastic and comprised of an inner hollow hub 30, supported by webs29, drive gear teeth 32, the pinion 33 and the slip drive 34. Pinion 33is concentric with hub 30 and supported therefrom on a protruding rearface 30a by three hands 33a., 33b and 3 33e symmetrically disposedaround the circumference of the inner hub (FIGURE 3). The slip drive 34is housed within the hollow hub 30 and includes three arcuate fingers35, 36 and 37 respectively, which are located in one and the same radialplane within the hollow hub, and are each integrally formed andsupported at one end by one of the pinion supporting hands. Theunsupported end portions 35a, 36a and 37a of the fingers are formed suchthat they will engage and be expanded outwardly toward the wall 30h ofhollow hub 30 when a protruding hub 27a of the take-up spool 27 isinserted into the hollow hub 30 (FIGURES 4 and 5). Consequently, thetakeup spool is frictionally coupled to the yfingers and rotates insynchronism with take-up spool gear 28, on a frame mounted spindle 48,as long as there is no load imposed on the take-up spool. However,whenever the index rollers grip the ribbon, a load is produced which istransmitted to the take-up spool and causes the spool to slip withrespect to the rotating take-up spool drive gear, which rotates througha greater angular distance than the index roller, as hereinbeforedescribed.

Since the ribbon is being urged in the wind direction, the length 24 ofribbon between the indexing roller and the take-up spool (FIGURE 2) willbe maintained in a relatively taut condition. Furthermore, a brake orno-back assembly -43 prevents the take-up spool gear from rotating inthe reverse or clockwise direction, as viewed in FIG- URE 2, therebysustaining the length 24 of ribbon taut. Brake assembly 43 is comprisedof an arm. 42 pivotally mounted to the machine frame by Imeans of a boss47 and a stud 44. A spring 45 secured to the lower end 42b of the armand to a frame supported stud 46 biases the upper end 42a of arm 42 intoengaging outer ring 31 of the take-up spool. The upper arm end 42a hasan arcuate shape which is eccentric with respect to the pivotal mountingof arm 42 whereby the take-up spool gear is free to rotate in acounterclockwise direction and prevented from rotating in a clockwisedirection.

The take-up spool 27 may be any conventionally shaped spool consistingof two end flanges separated by a hub for accommodating the ribbon,provided one of the flanges has a protruding hub for engaging the slipdrive. Thus, for example, the spool may be similar to that disclosed incopending patent application Ser. No. 461,653, led Ilune 7, 1965, byCarl A. Geissler, now Patent No. 3,317,155 issued May 2, 196'7, exceptthe grooved pulley 24 described in the reference application must bereplaced with a hub similar to hub 27a of this application. It is, ofcourse, axiomatic that one of the ribbon spool flanges may be formed tohouse the integral slip drive instead of the drive gear, in which casethe take-up spool gear would have a hub for engaging the slip drive.

It will now appear that I have provided a slip drive that attains theseveral objects set forth above in a thoroughly practical and eicientmanner.

The invention claimed is:

1. In a typewriter having, a carbon ribbon supply spool,

a ribbon vibrator,

a pair of ribbon feed rollers for indexing the ribbon upon each typingstroke,

ribbon take-up means including a drive gear member and a take-up spoolmember each of which has a hollow hub concentrically mounted forrotation,

a drive shaft operable on each type stroke to rotate said drive gearmember,

and a gear train coupled to said drive gear member and said feed rollersto drive said feed rollers through a smaller angle than the angle saiddrive gear member rotates on each stroke,

the improvement comprising,

a slip drive having releasable securing means integrally formed andhoused within the hollow hub of one of said members, said releasablesecuring means including a plurality of cantilever mounted arcuatelyshaped ngers extending radially in the same circular plane from one of aplurality of hands symmetrically disposed around the circumference ofsaid hollow hub housing said releasable securing means to frictionallyengage the hub of the other member, whereby said releasable securingmeans will rotate said take-up spool member with said drive gear memberand slip in response to load on said takealp spool member.

2. A mechanism as recited in claim 1 including a braking assemblycomprising a pivotally mounted arm having an arcuate end eccentricallyformed to frictionally engage said take-up spool member and therebyprevent said take-up spool member from rotating in any direction otherthan a wind direction, and a spring means connected to said arm forbiasing said arcuate end into engagement with said takeaup spool member.

References Cited UNITED STATES PATENTS 851,988 4/1907 Howell 197-175 X871,373 ll/l907 Sponsel 197-151 2,811,235 10/1957 Geissler 197--151 X3,120,177 2/1964 Clark 197-175 X 3,176,819 4/1965 Bloom et al 197-133ROBERT E. PULFREY Primary Examiner.

ERNEST T. WRIGHT, Assistant Examiner.

